Page 301 - Practical Well Planning and Drilling Manual

Section 2 revised 11/00/bc 1/17/01 12:04 PM Page 277

Cementing Program [ ]
2.7.5

Fig. 2-10 Section through the Jetting Tool

Slurry properties. The considerations discussed previously apply to
this slurry, with respect to rheology, compatibility with mud and for-
mation, gas blocking if opposite a gas zone, free water, settling, and low
fluid loss.
Settling and mixing is minimized with increased yield point and
gel strength. However, high gel strength (or thixotropic slurries) may
lead to the slurry not properly filling the void left when the stinger is
pulled out.
Free water should be low and the slurry should not settle out sig-
nificantly during setting so that the top of the cement plug is hard.
Thickening time should not be excessive since long thickening times
will give more time for the plug to mix with mud. Ideally, good com-
pressive strength will buildup by the time the stinger has been pulled
out and the directional assembly run in so that time waiting on cement
is minimized. Running a temperature survey will help this.
Slurry density should be close to the mud density to prevent set-
tling (covered in “Plug stability” within this subsection). Heavy slur-
ries combined with dispersants and retarders should be avoided
because they will settle downhole.

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